There are six major families of bacteriophages including Myoviridae (T-even bacteriophages), Styloviridae (Lambda bacteriophage groups), Podoviridae (T-7 and related bacteriophage), Microviridae (X174 group), Leviviridae (for example, E. coli bacteriophage MS2) and Inoviridae as well as coliphages, in general. Other bacteriophage families include members of the Cystoviridae, Microviridae, and Siphoviridae families.
Bacteriophage has been used therapeutically for much of this century. Bacteriophage, which derive their name from the Greek word “phago” meaning “to eat” or “bacteria eaters”, were independently discovered by Twort as well as by D'Herelle in the first part of the twentieth century. Early enthusiasm led to the use of bacteriophage as both prophylaxis and therapy for diseases caused by bacteria. However, the results from early studies to evaluate bacteriophage as antimicrobial agents were variable due to the uncontrolled study design and the inability to standardize reagents. Later, in better designed and controlled studies, it was concluded that bacteriophage were not useful as antimicrobial agents (Pyle, N. J.,J. Bacteriol, 12:245-61 (1936); Colvin, M. G., J. Infect. Dis., 51:17-29 (1932); Boyd et al., Trans R. Soc. Trop. Med. Hyg., 37:243-62 (1944)).
This initial failure of phage as antibacterial agents may have been due to the failure to select for phage that demonstrated high in vitro lytic activity prior to in vivo use. For example the phage employed may have had little or no activity against the target pathogen, or they may have been used against bacteria that were resistant due to lysogenization or the phage itself may have been lysogenic for the target bacterium (Barrow, et al., “Bacteriophage therapy and prophylaxis: rediscovery and renewed assessment of potential” Trends in Microbiology, 5:268-71 (1997)). However, with better understanding of the phage-bacterium interaction and of bacterial virulence factors, it has been possible to conduct studies which demonstrated the in vivo anti-bacterial activity of the bacteriophage (Asheshov, et al., Lancet, 1:319-20 (1937); Ward, W. E., J. Infect. Dis., 72:172-6 (1943); Lowbury, et al., J. Gen. Microbiol., 9:524-35 (1953)). In the U.S. during the 1940's the Eli Lilly Co. commercially manufactured six phage products for human use, including preparations targeted towards Staphylococci, Streptococci and other respiratory pathogens.
With the advent of antibiotics, the therapeutic use of phage gradually fell out of favor in the U.S. and Western Europe, and little subsequent research was conducted. However, in the 1970's and 1980's bacteriophage therapy continued to be utilized in Eastern Europe, most notably in Poland and the former Soviet Union. Alisky et al. conducted a review of all Medline citations where bacteriophage was employed therapeutically from 1966 to 1996 (Alisky et al, “Bacteriophages show promise as antimicrobial agents.” J. Infect., 36-5-15 (1998)). There were twenty-seven papers from Britain, the U.S.A., Poland and the Soviet Union.
There are also several British studies describing controlled trials of bacteriophage raised against specific pathogens in experimentally infected animal models such as mice and guinea pigs (See, e.g., Smith, H. W., and M. B. Huggins “Successful treatment of experimental Escherichia coli infections in mice using phages: its general superiority over antibiotics” J. Gen. Microbiol. 128:307-318 (1982); Smith, H. W., and M. B. Huggins “Effectiveness of phages in treating experimental E. coli diarrhea in calves, piglets and lambs” J. Gen. Microbiol, 129:2659-2675 (1983); Smith, H. W. and R. B. Huggins “The control of experimental E. coli diarrhea in calves by means of bacteriophage” J. Gen. Microbiol., 133:1111-1126 (1987); Smith, H. W., R. B. Huggins and K. M. Shaw “Factors influencing the survival and multiplication of bacteriophages in calves and in their environment” J. Gen. Microbiol., 133:1127-1135 (1987)). These trials measured objective criteria such as survival rates. Efficacy against Staphylococcus, Pseudomonas and Acinetobacter infections were observed. These studies are described in more detail below.
One such study concentrated on improving bioavailability of phage in live animals by modifying the bacteriophage (Merril, C. R., et al., “Long-circulating bacteriophage as antibacterial agents” Proc. Natl. Acad. Sci. USA, 93:3188-3192 (1996)). Reports from the U.S. relating to bacteriophage administration for diagnostic purposes have indicated phage have been safely administered to humans in order to monitor humoral immune response in adenosine deaminase deficient patients (Ochs, et al., “Antibody responses to bacteriophage (Φ174 in patients with adenosine deaminase deficiency” Blood, 80:1163-71 (1992)) and for analyzing the importance of cell-associated molecules in modulating the immune response in humans (Ochs, et al., “Regulation of antibody responses: the role of complement and adhesion molecules.” Clin. Immunol. Immunopathol., 67:S33-40 (1993)).
Additionally, Polish, Georgian, and Russian papers describe experiments where phage was administered systemically, topically or orally to treat a wide variety of antimicrobial resistant pathogens (See, e.g., Shabalova, I. A., et al., “Pseudomonas aeruginosa bacteriophage in treatment of P. aeruginosa infection in cystic fibrosis patients,” Abstr. 443. In Proceedings of IX International Cystic Fibrosis Congress, Dublin, Ireland; Slopek, S., et al., “Results of bacteriophage treatment of suppurative bacterial infections I. General evaluation of the results.” Archivum. Immunol. Therapiae Experimental, 31:267-291 (1983); Slopek, S., et al., “Results of bacteriophage treatment of suppurative bacterial infections in the years 1981-1986” Archivum Immunol. Therapiae Experimental, 35:569-83 (1987)).
Infections treated with bacteriophage included osteomyelitis, sepsis, empyema, gastroenteritis, suppurative wound infection, pneumonia and dermatitis. Pathogens treated with the bacteriophage include Staphylococci, Streptococci, Klebsiella, Shigella, Salmonella, Pseudomonas, Proteus and Escherichia. Articles have reported a range of success rates for phage therapy between 80-95% with only rare reversible allergic or gastrointestinal side effects. These results indicate that bacteriophage may be a useful adjunct in the fight against bacterial diseases.
Despite the use of bacteriophage for the treatment of diseases in humans, there remains in the art a need for the discovery of novel bacteriophage and methods for using these bacteriophage in several critical areas. One significant need concerns the treatment of processed or unprocessed food products to treat or prevent colonization with undesirable Salmonella such as pathogens responsible for foodborne illness and food spoilage organisms. A second critical area of need concerns the removal of undesirable bacteria from industrial environments such as food processing facilities to prevent colonization thereof. A third critical area of need concerns the removal of antibiotic resistant organisms from environments where they may be passed to susceptible humans and animals, such as hospitals, nursing homes, veterinary facilities, and other such environments. Finally, new bacteriophage and methods of using the same are needed for the treatment of human bacterial disease, particularly those diseases caused by antibiotic-resistant organisms.